1. Field of the Invention
One disclosed aspect of the embodiments relates to an exposure apparatus and a device manufacturing method.
2. Description of the Related Art
Recently, flip-chip mounting is being employed more frequently for the mounting of semiconductor devices. The manufacturing operations of a semiconductor device performed based on flip-chip mounting include an operation of forming a solder ball on the device.
An example of a known method for forming a solder ball is a plating method. In a plating method, in order to bring a conductive film formed on the wafer (substrate) into contact (be in a conductive state) with the electrode in the plating apparatus, the portion of the resist formed on the conductive film for contacting the electrode has to be peeled away.
If the resist is a negative resist, this process may be performed by preventing the exposure light from irradiating a circumferential portion of the wafer. Specifically, this process may be performed by shielding the circumferential portion of the wafer. For example, U.S. Pat. No. 6,680,774 discusses a technique in which a light shielding plate is arranged on a wafer during exposure.
Japanese Patent Laid-Open No. 2005-286062 discusses an imprinting apparatus that transfers a mold pattern onto a resist by irradiating UV-rays on the resist that is arranged on a wafer in contact with a mold. In the technique discussed in Japanese Patent Laid-Open No. 2005-286062, in order to define irradiation regions respectively corresponding to shot regions of peripheral parts of the wafer, four light shielding plates having arcs respectively corresponding to the outline of regions corresponding to first to fourth quadrants on a wafer are driven in an X-axis direction and a Y-axis direction, respectively.
If a light shielding plate is arranged on a wafer like in U.S. Pat. No. 6,680,774, since the light shielding plate has to be retracted each time the wafer is replaced, there are restrictions in terms of space and throughput.
Rather than arranging the light shielding plate on the wafer, the light shielding plate could be arranged on a face that is optically conjugated with the wafer, as discussed in Japanese Patent Application Laid-Open No. 2005-286062, and could shield a peripheral region of the wafer with this light shielding plate. In such a technique, the light shielding plate is positioned so that the distance from the periphery of the wafer to the boundary of the peripheral region is constant (i.e., a peripheral region on the inner side is shielded for a predetermined width from the periphery of the wafer) based on the position of a periphery shot region on the wafer for each periphery shot region.
However, when shielding the wafer based on its outer shape as a reference, the distance between a drive reference position of the light shielding plate drive unit for driving the light shielding plate and the actual center position of the wafer (position that will serve as the exposure reference) is not always the same.
If the distance between the drive reference position of the light shielding plate and the center position of the wafer is misaligned, when the light shielding plate is positioned based on the position of the periphery shot region on the wafer, the light shielding plate will be mispositioned by that displacement amount. Consequently, the distance from the periphery of the wafer to the boundary of the peripheral region is different for each periphery shot region, so that the width of the peripheral region shielded by the light shielding plate may not be set the same.